Geological setting and age


The base of the Ludlow Bonebed Member represents the base of the Downton Castle Sandstone Formation and the beginning of the Prídolí Stage in the Upper Silurian. Most organic-rich deposits within this sedimentary succession occur approximately 1.6m above the basal bone bed (Dunlop, 1996) and the lagerstätte occurs 0.15-0.2m above the top of the basal bone bed.

Antia (1979) has intertpreted the Ludlow Bonebed as resting conformably on top of Ludlovian sediments and recognises four distinct facies termed A, B, C and D:

Facies A- Interbedded quartz silts with few shell bands, 1-15mm thick, posessing erosive bases and frequently containing ostracods and fish scales. Units having erosive bases and lacking lenticular or flaser bedding are interpreted as representing storm events.

Facies B-Interbedded quartz-rich silts exhibting lenticular bedding between clayey silts (Antia, 1979). Bioturbation is common with abundant Chondrites traces. Fish scales occasionally form thin bone beds 1-6mm thick

Facies C-The sediments lying above the Ludlow Bonebed sensu stricto contain several small bone beds and occur in a sequence of lenticular and flaser bedded units with discontinuous rippled sand sheets typical of an intertidal environment. Burrows are often present at the base of the thin bone beds and are typically infilled with vertebrate sand material containing thelodont scales and phosphatic nodules.

Facies D-Mud-cracked and channelised silts and clays exhibiting flaser bedding occur 1.0m above the Ludlow Bonebed sensu stricto. The small channels are frequently infilled with bioclastic material.

 

 Stratigraphy of Ludlow Bonebed Lagerstätten


 Ludford Lane Bonebed Index page

Location.

Fauna and flora

 Taphonomy

 References and links